What is the order of drilling?

Drilling is a crucial part of numerous industries, at Rotabroach we provide the tools for companies across the world to complete large-scale projects to the highest standards, here&#;s how:

Which industries use Rotabroach products?

Rotabroach products can be found in a variety of different industries, from construction and rail, to shipbuilding, oil and gas production and many, many more. These sectors rely on quality, hard-wearing products, capable of performing in the most difficult environments without compromise. For this reason, Rotabroach has been producing market-leading magnetic drills, annular cutters and a wide range of related equipment to help businesses complete ambitious projects and perform critical maintenance with tools they can rely on.

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Why Rotabroach?

With an esteemed reputation built by decades of consistent quality, Rotabroach has established itself as the premier name in the mag drill industry, along with market-leading annular cutters and other related products. This rich heritage, combined with cutting-edge innovation, makes Rotabroach a key part of multiple industries, relied upon to deliver quality and performance in the most challenging environments.

Powering the drilling industry

Natural resources drilling is a critical part of the world economy, with more than three-quarters of the United Kingdom&#;s primary energy needs accounted for by oil and gas in recent years, similarly to many other countries.

Therefore, the oil industry and natural gas industry require efficient, consistent maintenance and large-scale new projects require extremely high levels of planning and careful execution. Rotabroach&#;s range of specialist adaptable drills are perfectly suited to the unique challenges of these industries and the complex environments they tackle on a daily basis.

So, how does the drilling process work?

The drilling process for oil and natural gas is essentially the same and can be simplified into the following stages:

1. Preparing the rig site
2. Drilling
3. Cementing and Testing
4. Well Completion
5. Fracking
6. Production and Fracking Fluid Recycling
7. Well Abandonment and Land Restoration

These stages are are consistent between both oil and natural gas drilling, with drilling operations started and carried out in similar ways. To understand Rotabroach&#;s place in all this, it is key to know these stages in more detail.

Preparing the drilling rig site.

Before an organization can begin drilling operations, they must first produce the infrastructure necessary to facilitate safe, responsible and compliant drilling. This includes providing pads and access roads, as well as water and electricity facilities. Having planned and surveyed the site, as well as providing this infrastructure, safety procedures and obtaining relevant permits beforehand, the start of the drilling process can begin.

Drilling

With the preparatory stage of the drilling site completed, it is then possible to begin drilling the initial surface hole. This is drilled past the deepest fresh water aquifer (to avoid contaminating water supplies), before the drill pipe is removed and replaced with steel pipe, otherwise known as &#;surface casing&#;. In order to keep the drill bit cool during this process, a special drilling mud is used to regulate the temperature of the drill bit, as well as providing stability to the walls of the borehole and removing loose rocks.

Cement is then pumped down this surface casing, and back up between the casing and the borehole, creating a vital impermeable barrier between the bore hole and nearby fresh water sources. Before continuing, testing takes place to ensure than the cement barrier is completely impermeable and there is no risk of contamination. This approach, known as vertical drilling, is an essential part of oil or natural gas production.

Alongside this, horizontal drilling is another approach which is applied in the oil and natural gas sector. When drilling for hydrocarbons in a shale formation it is necessary to drill horizontally, this begins with a vertically-drilled well which drills to a specific depth, called the &#;kick-off point&#;, where the well bore begins to curve horizontally.

A key advantage of this approach is its potential to drill several laterals from a single surface drilling pad, this minimizes the impact and scale of activity on the above drilling rig, therefore reducing disturbance. When the target distance is reached, drill pipe is removed and more steel casing is inserted throughout the well bore, cemented in place similarly to the vertical drilling process. After this stage is completed, the well completion process can take place.

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Well Completion

Having produced the final casing, the next stage is to create a connection between this surface casing and the rock layer holding the oil and gas. To do this, a specialized &#;perforating gun&#; is lowered to the rock layer, firing to create holes between the casing pipe and into the target rock, piercing the cement layer. These perforating holes, only inches long, do not cause any detectable activity on the surface. Once completed, the perforating gun is removed and the next stage, hydraulic fracturing, can begin.

Hydraulic fracturing

Hydraulic fracturing, otherwise known as fracking, is the next stage of the oil and natural gas drilling process. This begins with stimulation fluid, a mixture of <90% water and sand (with some chemical additives) is pumped under high pressure into deep underground reservoir formations. The chemicals used in fracturing fluid are for lubrication and preventing bacteria formation. They are non-hazardous, low concentration and are necessary to improve the performance and efficiency of hydraulic fracturing.

The stimulation fluid is pumped through the perforations made by the perforating gun, this will hydraulically fracture the shale rock which contains the target natural gas. The sand remains in the rock fractures to keep them open whilst pump pressure is relieved, allowing previously trapped oil and gas to flow to the well bore.

Oil and natural gas production

Once the hydraulic fracturing process has taken place, the well can begin to produce oil. The oil and natural gas flow from the well bore and the fracturing fluid is recovered. During the initial production of a well, roughly 25-75% of fracturing fluid is recovered and either recycled in other fracturing operations, or disposed of in a fashion complying with government environmental regulations.

The process of developing a well, as described, typically takes roughly 3-5 months in total with the following timeline;

• Preparing the site: a few weeks
• Drilling the well: eight to twelve weeks
• Completing the well and stimulation: one to three months

This relatively short timeline carries a significant financial investment, however it has the potential to produce a well which can provide oil and gas for decades to come. However, when all of the economically viable resources have been depleted, drilling rigs must be decommissioned in a specific process.

Well Abandonment

Having extracted all of the viable oil and natural gas, the land used by the drill site must be returned to its original state prior to the operation&#;s start. This is achieved by filling the well with cement and cutting all drill pipe off ~6 feet below ground level. Having filled the surface hole all surface equipment will be removed and any well pads filled in. This returns the land to its initial state, with minimal evidence of a well site having existed.

So, how does Rotabroach fit into this?

As discussed, drilling for oil and gas requires significant amounts of construction and infrastructure. Working with steel structures, hard alloys and tight spaces requires a special kind of equipment. This is where Rotabroach comes in; producing dependable, high-performance equipment, Rotabroach supplies these industries with the tools to take on specialized challenges where competitors cannot. For example, the ATEX approved Eagle and Raven drills provide the necessary power in combustible environments, ensuring user safety and minimizing risk.

Offshore drilling takes these unique challenges and amplifies them, introducing difficult environmental elements into the mix and pushing tools to their limit. Luckily, Rotabroach tools are prepared for any environment, able to maintain performance where others fail, the superior build quality of Rotabroach products ensures that they remain the market-leading choice for drilling applications.

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We have discussed the components of the drilling rig, now let&#;s discuss the drilling process itself. An oil or gas well is drilled in a very ordered sequence. The steps in this sequence are almost universally applied to the drilling of all wells.

1. Plan the Well: As we have discussed, exploration well prospects are generated by exploration geologists; while development wells locations and objectives are generated by development geologists. Once the surface locations and well objectives are known, the geologists work with the drilling engineers to develop the detail drilling proposals. In addition, all permits (environmental, safety, regulatory, etc.) are acquired during the final stages of the planning process when a solid well proposal is developed.
2. Perform Shallow Gas Survey: To ensure there are no shallow gas hazards which may result in a kick or blow out, a shallow gas survey is performed to identify the locations and depths of any potential shallow gas hazards. Preliminary surface locations and well trajectories may be altered from the original well proposal to avoid these shallow gas hazards.
3. Prepare the Wellsite: The site preparation involves building clearing land for use by the rig, building access roads to the well site or well pad, construct infrastructure for water, water disposal, and electricity, dig and line all mud pits to prevent ground water or water table contamination, dig reserve pits for cutting storage (for eventual disposal), and drill the holes which will eventually become the rat hole and the mousehole. The site preparation may involve multiple contractors and companies to perform all of the required work. As we discussed in earlier lessons, a lot of site-preparation time and the environmental footprint can be minimized if multi-well pads are used in the field development.
4. Set the Conductor Casing: Prior to the arrival of the drilling rig, an Auger Unit (in hard rock regions) will drill a large diameter hole capable of accommodating 18 in. to 36 in. conductor casing (see Figure 9.16). In soft rock regions or at offshore locations, a diesel hammer may be used to hammer the conductor casing into place. The conduct casing may go to depths of 40 to 300 ft depending on the location. The conductor casing is typically set through the top soil and loose rocks to the bed rock. The objective of the conductor casing is to isolate the wellbore from the top soil to ensure that loose debris does not enter the well during early drilling operations. The conductor casing is then cemented into place.
5. Move-In and Rig Up (MIRU): Once the wellsite is prepared and the conductor casing is in-place, the rig is brought on location. Most land rigs, particularly those in North America, are transported on multiple trucks. Once on the well site or well pad, the rigging-up process begins. Rigging up the well consists of taking the rig modules from the trucks and assembling the rig. Included in the rigging up process is setting-up all of the rig systems and testing these systems. Here is a YouTube video, "Rigging up Land Drilling Rig" (3:35), showing the Rigging Up process of the derrick:
   Transporting and assembling the rig may take 50-75 workers (two crews), 35 &#; 40 vehicles, and take up to four days. If a multi-well pad is used, once the rig is rigged-up for the first well, then the rig can simply be skidded over to the next location without having to dig-down.
6. Spud the Well: After the rig has been inspected and all of the systems tested the well can be Spudded. Spudding a Well refers to starting the rotary drilling operations for that well.
7. Drill Down to the Surface Casing Depth: The first section of the well to be drilled is the section that goes down to the pre-determined surface casing depth (Casing Point). Obviously, for this section of the wellbore, the drill bit diameter must be smaller than the ID (inner diameter) of the conductor casing. In this shallow section of the wellbore, fresh water aquifers (both for personal and municipal use) exist. As discussed earlier, shallow gas hazards may also exit. The objectives of drilling this first section of the well is to allow the setting and cementing of the surface casing to:
   1. protect the fresh water aquifers by placing a steel and concrete barrier to isolate the water table from the well;
   2. protect the well from the aquifer (cutting of the drilling fluids with fresh water);
   3. protect the well from shallow gas hazards.
   This section of the well is drilled through the most environmentally sensitive depths. Consequently, when this section of the hole is drilled, it is typically drilled with the most environmentally friendly drilling fluid (possibly either air or fresh water) and cased and cemented as soon as possible to alleviate any potential of contaminating fresh water aquifers. By running the surface casing string, we are putting the environmentally sensitive water table behind pipe and protecting it from future well (drilling and production) activities.
8. Run and Cement the Surface Casing: Once the surface casing point is reached, the surface casing is run into the wellbore and cemented into place. This process is performed by:
   1. Pulling Out of Hole (POOH): Tripping out of the hole with the drill pipe to remove it from the wellbore during cementing operations;
   2. running the surface casing;
   3. pumping a cement slurry down the interior of the casing;
   4. chasing the cement with drilling fluid to displace the cement up into the annular space between the casing string and the wellbore (rock);
   5. allowing time for the cement to Cure (harden).
   Cementing is a common activity planned and implemented by drilling engineers, and you will learn a lot more of the details in your future drilling courses. The following YouTube video, "Running Casing" (7:01), shows the cementing process (note: this is a commercial video for Frank&#;s International):
    
9. Continue this Process to Drill to the Next Casing Point: This drilling process is continued to the next pre-determined casing point. The selection of these intermediate-string casing points is beyond the scope of the class, but the criteria are based on the mud weight, the Fracture Pressure of the formations to be drilled (the pressure that causes the formation to fracture), the locations of any Lost Circulation Zones, and the locations of any High Pressure Zones. As we discussed earlier, any of these situations may result in a kick and a potential blowout. The objectives of the intermediate casing strings are:
   1. isolate unstable hole sections behind pipe;
   2. isolate lost circulation zones behind pipe;
   3. isolate under-pressured zones behind pipe (prevent lost circulation);
   4. isolate over-pressured zones behind pipe (prevent a kick);
   5. isolate multiple producing zones
10. Continue this Process to Drill to each Casing Point: This process is repeated for each of the planned casing points. Obviously, as successive casing strings are run and cemented into place, smaller diameter tools and drill bits must be used for continued drilling operations. As we discussed earlier, the two most important drilling parameters within the Driller&#;s control to maximize the Rate of Penetration (ROP) of the drill bit are the weight-on-bit and the rotational speed of the rotary system in Revolutions per Minute (RPM).
11. Continue this Process to Drill to Total Depth (TD): Once the final intermediate casing string is run and cemented, the drilling process is continued until the well reaches the TD (Total Depth) of the well. At this point, the well is said to be TD&#;ed.
12. Log the Well with Open-Hole Logs: At this point, the sand face is exposed to the well and Open-Hole Logging Tools can be run in the well. Open-hole logs are used to measure certain properties of the subsurface formation that are of interest to the geologists and engineers working on the well and the reservoir.
13. Run and Cement the Production Casing String or Liner: If a production casing string or production liner is to be used in the completion, then they are run and cemented at this time.
14. Compete the Well: Install the well completion as discussed in earlier lessons:
    1. tubing
    2. gravel packs
    3. packers
    4. sliding sleeves
    5. stimulation
       1. acidize the well
       2. hydraulically fracture the well
    6. artificial lift
15. Rig Down and Move Out

Source: Greg King © Penn State, licensed CC BY-NC-SA 4.0

Finally, here is a YouTube video, "Drilling Animation" (5:58), showing the entire drilling process. This animation is from Chesapeake Energy, and it discusses the drilling process for a Marcellus Shale well:
 

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